I have never seen anything like it...



At first I thought my props are broken. Or gimbal.
But the craft was fully functional, and I realized it has something to do with the angle to the Sun.
I still don't have a full explanation, only a theory.
I think it's a shadow in a foggy air, since it only appeared at the fog edge.

PS.
The fog bank was actually VERY thick, I cut a pretty long part from the ascent.

Well, at least the last half has some amazing views.  But yes, i wonder what those bands are caused by.

fog is moisture (water) can damage electronics

Looks like a refresh rate almost,    maybe the water got into the electronics.

It seems obvious to me that it's the props casting shadows across the lens. That's why they disappear while the camera is pointing towards the sun, then come back as you yaw far enough for the other side prop to start casting a shadow.

i think you should drop camera down a little its facing slightly upwards and you are getting shadows across your lens cover because flying directly into the sun.

It appears to me to be scan lines. Like when you try to video a tv screen. Do you have a filter on the lens?

I'll try again...

IT'S PROPS CASTING SHADOWS ON THE LENS

As you were.

I agree with the shadows theory. Looks like the fog created just enough media to go light/dark for the camera to capture it.

I have seen similar banding (I don't remember if it was in YT videos or my own ) but I always thought it was some sort of prop shadow too. The way the motion of the bands change reminds me of the way the apparent motion of a propellor changes in video as the propellor speed changes.

Sean-bumble-bee Posted at 1-8 09:34
I have seen similar banding (I don't remember if it was in YT videos or my own ) but I always thought it was some sort of prop shadow too. The way the motion of the bands change reminds me of the way the apparent motion of a propellor changes in video as the propellor speed changes.

I think the reason I have never seen this before is, well, I only flew through the fog twice in my life before this occurrence, and each time I was facing in such a direction that the banding shadows did not present themselves. And once you’re really clear of the fog layer, it just does not happen regardless of the angle.
So I guess it was just my luck to be at that angle during the ascent this time.

DarthSLR Posted at 1-8 08:58
I agree with the shadows theory. Looks like the fog created just enough media to go light/dark for the camera to capture it.

Nope. Nothing to do with the fog itself. There might be some effect from slight condensation misting on the front glass increasing the brightness where the sun is hitting it, hence increasing the contrast of the stripes.

The biggest factor is how much of the point source the sun is as you emerge from the fog and the fact that it's at just the right angle to cast the shadows.

It's an interesting and bizarre looking effect, but completely expected given the scenario.
Edit to add clarity: To get fog to "go dark" like that you need to be casting a long shadow, deep into the volume of the fog. Not really the setup you have here. There is a lot of fog in shot beyond the reach of the props that is side lit by the bright sun. Any difference in brightness due to shadow cast by even 10cm of prop blade would be minimal. I hope that makes sense.

Sean-bumble-bee Posted at 1-8 09:34
I have seen similar banding (I don't remember if it was in YT videos or my own ) but I always thought it was some sort of prop shadow too. The way the motion of the bands change reminds me of the way the apparent motion of a propellor changes in video as the propellor speed changes.

Yeah, that was what gave it away to me too. Then as Darth yawed "through" the sun and it disappeared, then came back as the other prop caused the same shadow, it was obvious.

Prop shade.

Nicodema Posted at 1-8 10:27
Nope. Nothing to do with the fog itself. There might be some effect from slight condensation misting on the front glass increasing the brightness where the sun is hitting it, hence increasing the contrast of the stripes.

The biggest factor is how much of the point source the sun is as you emerge from the fog and the fact that it's at just the right angle to cast the shadows.

I think if you look at his horizon its pretty clear camera is facing up and reflection comes easy if camera was slightly down this would disappear. You can point M3 camera pretty high up .

Prop shadows! It's rare with m3 but happened to me too

alex_markov Posted at 1-10 02:46
Prop shadows! It's rare with m3 but happened to me too

I think this would happen to any drone whose props are relatively close to the camera and cast shadows in front of it. It just needs proper amount of mist for it it to happen.

DarthSLR Posted at 1-10 07:11
I think this would happen to any drone whose props are relatively close to the camera and cast shadows in front of it. It just needs proper amount of mist for it it to happen.

It's by design - that's why front arms are so back on M3 to avoid it - MP had issues, M2P had virtually None, Evo 2 pro was terrible in this respect and DJI FPV never had it and M3 very rare

I got some strange stuff flying into thick fog over a river, odd half circle at the bottom of the frame that seemed to be magenta, could not see it on rc pro in dlog

alex_markov Posted at 1-10 08:07
It's by design - that's why front arms are so back on M3 to avoid it - MP had issues, M2P had virtually None, Evo 2 pro was terrible in this respect and DJI FPV never had it and M3 very rare

I remember seeing something like that on MP, and yes, don't recall any on M2P.
But, again, a certain level of mist is apparently required, and I almost never fly in one, if only for the reason to NOT damage the craft.

pistolpete Posted at 1-10 08:22
I got some strange stuff flying into thick fog over a river, odd half circle at the bottom of the frame that seemed to be magenta, could not see it on rc pro in dlog

The current DLOG view on RCPro is so bad, no wonder you could not see it. You can barely see the subject, and only the general shape at that.

I agree with all of the others about it being prop shadows.  However, its not just prop shadows, it is the shadows in relation to having a very fast shutter speed.  If you had the shutter speed set to 2x the frame rate (i.e. frame rate at 30fps, Shutter Speed at 1/60), then you would not have seen this issue.  This is generally referred to as the 180 rule and helps to introduce an appropriate amount of motion blur.  If you follow this, you will not get the prop shadows seen in your video.

KlooGee Posted at 1-10 09:12
I agree with all of the others about it being prop shadows.  However, its not just prop shadows, it is the shadows in relation to having a very fast shutter speed.  If you had the shutter speed set to 2x the frame rate (i.e. frame rate at 30fps, Shutter Speed at 1/60), then you would not have seen this issue.  This is generally referred to as the 180 rule and helps to introduce an appropriate amount of motion blur.  If you follow this, you will not get the prop shadows seen in your video.

I agree. the props frequency definitely has something to do with it.
You can see in my OP video that shadow appears and disappears while the angle and other conditions do not change, only as a result of my vertical movement, which affects the prop speed.
So, yeah, multiple factors here.

Lower your SS in order to "blend" the frames...With a SS at 1/50 you will have no issues like this....because SS is very high, the frames recorded have differences and the output is like this...
You still can save the picture with a tool named Flicker Free, or you can use the DaVinci tool for deflicker and blend 2 delayed by 1 frame clips, and result to be output using Blend method, not Optical Flow (in this cases Optical Flow will make a real mess).

KlooGee Posted at 1-10 09:12
I agree with all of the others about it being prop shadows.  However, its not just prop shadows, it is the shadows in relation to having a very fast shutter speed.  If you had the shutter speed set to 2x the frame rate (i.e. frame rate at 30fps, Shutter Speed at 1/60), then you would not have seen this issue.  This is generally referred to as the 180 rule and helps to introduce an appropriate amount of motion blur.  If you follow this, you will not get the prop shadows seen in your video.

Can you explain why the shutter speed being twice the frame rate would make the shadows disappear please?
That's a genuine question because at the moment my thinking is that a change in shutter speed would still capture them though they might be seen in a different part of the image or behave differently. This presumes the shadows are real and sweep across the cameras field of view.

Nicodema Posted at 1-8 03:01
It seems obvious to me that it's the props casting shadows across the lens. That's why they disappear while the camera is pointing towards the sun, then come back as you yaw far enough for the other side prop to start casting a shadow.

This is the correct answer

Geo_Drone Posted at 1-13 02:20
Lower your SS in order to "blend" the frames...With a SS at 1/50 you will have no issues like this....because SS is very high, the frames recorded have differences and the output is like this...
You still can save the picture with a tool named Flicker Free, or you can use the DaVinci tool for deflicker and blend 2 delayed by 1 frame clips, and result to be output using Blend method, not Optical Flow (in this cases Optical Flow will make a real mess).

I would still see the shadows on RC screen, since I can't control SS that one, can I?

DarthSLR Posted at 1-13 08:48
I would still see the shadows on RC screen, since I can't control SS that one, can I?

Depends on your screen refresh rate, but probably not as you "see" on screen what the sensor sees but with lower res. So you should see if the propeller shadow is gone.

To answer to another question here:
Each image in video have a SS and FPS. The FPS is how many frames are taken over a second, the SS is how many times the shutter open and close in front of sensor (mechanically or electronically, no matter).
Now for logical part for beginners:
- The propellers have a high speed, creating a shadow each time the propeller cut the light that goes to sensor...
- Do you see with naked eye this directly? No...why? Because your eye is "blending" the image...how to do this also with the "electronic eye" of a drone? Easy:
* Lower the FPS to 25 - will take each second 25 frames, instead of 30-60-...., meaning that will "blend more" each second
* Lower your SS to 1/50 - as for 180 degree rule, but also because your shutter being more slow, will remain open long enough to blend the light...is like when you make pictures with your camera at night, more you keep the SS, more light is recorded and more blended is the image.

So...in order to minimize or even eliminate this shadows from props, you need to go lower with SS and FPS. Of course, in order to keep the same light and not to have an over-exposure, you need a ND Filter...This is why all says "Put a ND Filter"...not because your ND filter is magic and take the propeller shadow away, but because your camera is lowering the SS and "blends" the image more.
Cheers.

Sean-bumble-bee Posted at 1-13 04:20
Can you explain why the shutter speed being twice the frame rate would make the shadows disappear please?
That's a genuine question because at the moment my thinking is that a change in shutter speed would still capture them though they might be seen in a different part of the image or behave differently. This presumes the shadows are real and sweep across the cameras field of view.

Shutter speed makes a huge difference in the way your eye perceives things.  For a simplified comparison, go to the 12:28 mark of this video and compare the difference in how the fan blades look.  And that is just with a 1/800 shutter speed compared to a 1/2000 or similar.  If interested, the full fan demonstration with different shutter speeds starts at about the 8:05 mark.

Keep in mind the fan blades are huge in comparison to 2 little tiny props and are going significantly slower.  If you use a proper SS, the props will completely disappear whether it is their shadow or literally the props themselves in view.

Sean-bumble-bee Posted at 1-13 04:20
Can you explain why the shutter speed being twice the frame rate would make the shadows disappear please?
That's a genuine question because at the moment my thinking is that a change in shutter speed would still capture them though they might be seen in a different part of the image or behave differently. This presumes the shadows are real and sweep across the cameras field of view.

The same concept (although at a different time interval) exists in long exposure photography.  With a long enough exposure, you can literally make people disappear from an image.

Ahhhh thanks, I think I misunderstood you post 26. Were you suggesting that the original shutter speed was too fast and that it should be SLOWED to twice the frame rate? If so that would be accompained by adjustment to either the senor's ISO and or (if possible) the camera's aperture?